Less effective meaning that the program does its job slower. From the way I read this it sounds like the original programmers used optimizations that worked wel

Less effective meaning that the program does its job slower. From the way I read this it sounds like the original programmers used optimizations that worked well on older processors but not newer ones. For instance you might optimize one way for a pentium 4 but differently for an i7. It is not that the code for the P4 will not work on the i7 but the code is optimized for an older processor. Now this can be mitigated by the fact that the i7 is much improved over the P4 but you can get greater improvements by actually modifying the program source code as done by the software here. As for the billion dollar problem I would guess it (Bit rot) is that or more over the entire software industry.